Image processing apparatus

Abstract

An image processing apparatus for decoding a compressed image data, the image data being divided to a plurality of tiles, each of which is a basic unit of process in encoding or decoding process, said apparatus comprising: a detector which detects an existence status of ROI within said compressed image data based on a frequency transform coefficient of said tile for every tile; a determiner which determines whether each tile is a ROI tile composed of only ROI, a non-ROI tile composed of only non-ROI, or a ROI boundary tile composed of ROI and non-ROI based on said existence status of ROI detected by said detector; a processor which shifts only frequency transform coefficient of said ROI within each tile to lower bit side for said ROI tile and said non-ROI tile determined by said determiner, and which shifts frequency transform coefficients of both ROI and non-ROI within each tile to lower bit side.

1. An image processing apparatus for decoding image data comprising frequency transform coefficients, the image data being divided to a plurality of tiles, each of which is in an encoding or decoding process, the image processing apparatus comprising:
 a detector which detects an existence status of a ROI set within said image data; 
 a determiner which determines whether each tile is a ROI tile that is composed only of ROI coefficients, a non-ROI tile that is composed only of non-ROI coefficients, or a ROI boundary tile composed of both ROI coefficients and non-ROI coefficients based on said existence status of the ROI set detected by said detector; and 
 a processor which performs a specific process for frequency transform coefficients of the ROI set and a non-ROI set within each tile for luminance component and color difference components, 
 wherein said processor 
 shifts the frequency transform coefficients to a lower bit side for luminance components and for color difference components for each tile determined to be a ROI tile, 
 shifts the frequency transform coefficients to the lower bit side for color difference components for each tile determined to be a non-ROI tile, 
 shifts the frequency transform coefficients to a lower bit side for the luminance components and for the color difference components corresponding to the ROI set for each tile determined to be a ROI boundary tile, and 
 shifts the frequency transform coefficients to the lower bit side for the color difference components corresponding to the non-ROI set for each tile determined to be a ROI boundary tile. 
 
   
   
     2. The image processing apparatus according to  claim 1 , wherein said detector detects the existence status of the ROI set based on the frequency transform coefficients of said tile for every tile. 
   
   
     3. The image processing apparatus according to  claim 1 , wherein the processor shifts the frequency transform coefficients for the color difference components of the ROI boundary tiles and the non-ROI tiles such that the non-ROI of the image data after decoding is displayed in monochrome. 
   
   
     4. The image processing apparatus according to  claim 3 , wherein the processor shifts the frequency transform coefficients for the color difference components of the ROI boundary tiles and the ROI tiles such that the ROI of the image data after decoding is displayed in color. 
   
   
     5. An image processing apparatus for decoding image data comprising frequency transform coefficients, the image data being divided to a plurality of tiles, each of which in an encoding or decoding process, the image processing apparatus comprising:
 a detector which detects an existence status of a ROI set within said image data based on frequency transform coefficients of every tile; 
 a determiner which determines whether each tile is a ROI tile that is composed only of ROI coefficients, a non-ROI tile that is composed only of non-ROI coefficients, or a ROI boundary tile composed of both ROI coefficients and non-ROI coefficients based on said existence status of the ROI set detected by said detector; 
 a processor which performs a first process for each tile determined to be a ROI tile or a non-ROI tile, and which performs a second process for each tile determined to be a ROI boundary tile by said determiner; 
 said first process shifts the frequency transform coefficients to a lower bit side for each tile determined to be a ROI tile, and 
 said second process shifts the frequency transform coefficients to the lower bit side for each tile determined to be a ROI boundary tile. 
 
   
   
     6. An image processing apparatus for decoding image data comprising frequency transform coefficients, the image data being divided into a plurality of tiles, each of which is in an encoding or decoding process, the image processing apparatus comprising:
 a detector which detects an existence status of a ROI set within said image data; 
 a determiner which determines whether each tile is a ROI tile that is composed only of ROI coefficients, a non-ROI tile that is composed only of non-ROI coefficients, or a ROI boundary tile composed of both ROI coefficients and non-ROI coefficients based on said existence status of the ROI set detected by said detector; and 
 a processor which shifts frequency transform coefficients of said ROI set within each tile determined to be a ROI tile to a lower bit side, and which shifts frequency transform coefficients of both the ROI set and a non-ROI set within each tile determined to be a ROI boundary tile to the lower bit side. 
 
   
   
     7. The image processing apparatus according to  claim 6 , wherein said detector detects the existence status of the ROI set based on the frequency transform coefficients of said tile for every tile. 
   
   
     8. The image processing apparatus according to  claim 6 , wherein said processor shifts the frequency transform coefficients to the lower bit side for a tile determined to be a non-ROI tile which abuts with said ROI boundary tile. 
   
   
     9. The image processing apparatus according to  claim 6 , wherein the processor shifts the frequency transform coefficients for the ROI boundary tiles such that a bordering line around the ROI of the image data can be added. 
   
   
     10. The image processing apparatus according to  claim 6 ,
 wherein the determiner determines whether each tile is a non-ROI tile bordering a ROI boundary tile, and 
 wherein the processor shifts the frequency transform coefficients of a non-ROI tile bordering a ROI boundary tile to the lower bit side. 
 
   
   
     11. An image decoding apparatus for decoding a tile of image data comprising frequency transform coefficients, wherein the tile is one of a plurality of tiles of the image data, each tile being in an encoding or decoding process, the image decoding apparatus comprising:
 a dynamic range analyzer configured to analyze a dynamic range of the tile, wherein the dynamic range is based on a number of bits representing transform coefficients of the tile; 
 a determiner configured to determine whether the tile is a ROI tile that is composed of only ROI coefficients, a non-ROI tile that is composed of only non-ROI coefficients, or a ROI boundary tile that is composed of both ROI coefficients and non-ROI coefficients based on the dynamic range of the tile analyzed by the dynamic range analyzer; 
 a processor configured to reduce the transform coefficients of the tile based on whether the tile is determined to be a ROI tile, a non-ROI tile or a ROI boundary tile, and 
 wherein the processor is configured to reduce all transform coefficients of the tile by a predetermined reduction amount when the tile is determined to be a ROI boundary tile. 
 
   
   
     12. The image decoding apparatus according to  claim 11 , wherein the determiner is configured to
 determine that the tile is a non-ROI tile when the dynamic range of the tile is less than a predetermined dynamic range threshold, 
 determine that the tile is a ROI tile when the dynamic range of the tile is equal to or greater than the predetermined dynamic range threshold and there are no transform coefficients of the tile that is less than the predetermined dynamic range threshold, and 
 determine that the tile is a ROI boundary tile when the dynamic range of the tile is equal to or greater than the predetermined dynamic range threshold and there is at least one transform coefficient of the tile that is less than the predetermined dynamic range threshold. 
 
   
   
     13. The image decoding apparatus according to  claim 12 , wherein the predetermined reduction amount is equal to the predetermined dynamic range threshold. 
   
   
     14. The image decoding apparatus according to  claim 12 ,
 wherein the determiner is further configured to determine whether the tile is a border non-ROI tile that is composed of only non-ROI coefficients and borders at least one ROI boundary tile, and 
 wherein the processor is configured to reduce all of the transform coefficients of the tile by a predetermined reduction amount when the tile is determined to be a border non-ROI tile. 
 
   
   
     15. The image decoding apparatus according to  claim 12 ,
 wherein the transform coefficients of the tile include luminance and color difference transform coefficients, and 
 wherein when the tile is determined to be a ROI boundary tile, the processor is configured to
 reduce the luminance transform coefficients of the ROI set of the tile by a predetermined reduction amount, 
 reduce the color difference transform coefficients of the ROI set of the tile by the predetermined reduction amount, 
 leave unchanged the luminance transform coefficients of the non-ROI set of the tile, and 
 reduce the color difference transform coefficients of the non-ROI set of the tile by the predetermined reduction amount. 
 
 
   
   
     16. The image decoding apparatus according to  claim 15 , wherein the predetermined reduction amount is equal to the predetermined dynamic range threshold. 
   
   
     17. The image decoding apparatus according to  claim 15 , wherein when the tile is determined to be a ROI tile, the processor is configured to reduce the luminance and the color difference transform coefficients of the tile by the predetermined reduction amount. 
   
   
     18. The image decoding apparatus according to  claim 15 , wherein when the tile is determined to be a non-ROI tile, the processor is configured to leave unchanged the luminance transform coefficients of the tile, and to reduce the color difference transform coefficients of the tile by the predetermined reduction amount. 
   
   
     19. The image decoding apparatus according to  claim 12 ,
 wherein the transform coefficients of the tile include luminance and color difference transform coefficients, and 
 wherein the processor is configured to reduce one or both of the luminance and color difference transform coefficients of the tile such that the ROI of the corresponding image data after decoding is displayed in full color and the non-ROI of the corresponding image data after decoding is displayed in monochrome. 
 
   
   
     20. A method of processing image for decoding image data comprising frequency transform coefficients, the image data being divided to a plurality of tiles, each of which is in an encoding or decoding process, the method comprising steps of:
 detecting an existence status of a ROI set within said image data based on frequency transform coefficients of every tile; 
 determining whether each tile is a ROI tile that is composed only of ROI coefficients, a non-ROI tile that is composed only of non-ROI coefficients, or a ROI boundary tile composed of both ROI coefficients and non-ROI coefficients based on said existence status of the ROI set detected in said detecting step; and 
 performing a first process for said ROI tile and said non-ROI tile determined in said determining step, and performing a second process for said ROI boundary tile determined in said determining step; 
 said first process is shifting the frequency transform coefficients to a lower bit side for each tile determined to be a ROI tile, and 
 said second process is shifting the frequency transform coefficients to the lower bit side for each tile determined to be a ROI boundary tile.